A control apparatus for an internal combustion engine with a turbo-supercharger that includes a waste gate valve that opens and closes an exhaust bypass passage that bypasses a turbine has already been disclosed in, for example, Patent Document 1. According to the conventional control apparatus, a configuration is adopted so as to open a throttle valve as far as a substantially fully open position when an accelerator pedal is operated as far as a predetermined operation amount. Further, if the accelerator pedal is opened to a greater degree than the predetermined operation amount, a supercharging pressure is controlled by adjusting an opening degree of the waste gate valve so that a target supercharging pressure can be obtained that is in accordance with the detected operation amount of the accelerator pedal and the engine speed.
In an internal combustion engine with a turbo-supercharger, in a state in which the atmospheric pressure is low, such as in a highland region, in comparison to a state in which the atmospheric pressure is high (a standard state such as one atmosphere pressure), a pressure ratio (outlet pressure/inlet pressure) of a compressor of the turbo-supercharger increases in a condition in which an equivalent intake air amount (engine load factor) is obtained. That is, in a situation in which the atmospheric pressure is low, a range of control of the intake pressure by the turbo-supercharger increases when obtaining an equivalent supercharging pressure in comparison to a state in which the atmospheric pressure is high. Further, in general, the responsiveness of intake air amount control by a turbo-supercharger is lower than the responsiveness of intake air amount control by a throttle valve.
According to the technique disclosed in aforementioned Patent Document 1, when the accelerator pedal is opened to a greater degree than the aforementioned predetermined operation amount, the supercharging pressure (intake air amount) is controlled by adjusting the opening degree of the waste gate valve. That is, in this case, since it is not possible to secure a margin for control of the intake air amount (intake pipe pressure) by the throttle valve, intake air amount control is executed that is dependent on the turbo-supercharger with respect to which the responsiveness is low. Under a low atmospheric pressure, in comparison to the standard state, the throttle opening degree required to obtain the same intake air amount (engine load factor) increases. Therefore, under a low atmospheric pressure, a load region in which the necessity arises to perform intake air amount control that depends on the turbo-supercharger increases in comparison to the standard state. Consequently, under a low atmospheric pressure, the responsiveness with respect to an intake air amount when accelerating is likely to decrease in comparison to the standard state.
Including the above described document, the applicant is aware of the following documents as related art of the present invention.